Let's talk about FUNCTIONAL CAVES.

I have been pretty impressed with the 3D backgrounds I have seen on this site (and others) and I plan to do my own sooner than later.

One of the things I would like incorporate into my BG is something I am calling a "functional cave". I actually want a few, if they work...

The idea is to make a cave out of plastic pieces (cd cases, plastic bottles, pvc, etc) and then cover it up with concrete so it looks like natural rock. The functional part would be the built in ability to almost completely fill the cave with air (and drain it). I also wanna flush the cave with a rush of water to move whatever crap thats building up in there and get it out into the tank so it can be filtered.

I did a quick little graph drawing to show what I mean.

The red is the power head entrance which would have a screened tip so nothing can escape up the tube.

The orange line is airline tubing that goes from the highest point of the caves interior and exits out the top of the tank. This would have a valve at the end above the tank someplace.

The green is an air stone attached to an air pump.

Oh, and the blue is the actual structure (concrete).

On the left is front view. the black boxes are supposed to be entrances. i was gonna have two entrances into a single inner chamber

The right is a bisected profile view with the back side to the right and plumbing behind it.

Now, I had primitive set up like this in my old tank and it worked to get my eel to actually leave his cave when i wanted him to once in a while. Im sure it pissed him off too so i rarely did it.

I plan to bench test this system and then do it on a larger scale in my 130.

I'm wondering what you guys think and if anyone has done anything like this.

As always, all comments are welcome and thanks for any replies...

d200

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

When I say this, I'm not being condescending, I just don't know. What's the desire to have air in the cave?

He pretty much explains it in his post, it's two fold, one it can be drained and flushed to remove build up of debris easily and second for those pesky fish that refuse to leave it would provide an easy means to evict them...

I have seen people use balloons to make caves and rocks. Air the balloon up and form concrete around it. Then deflate the balloon and pull it out. Might be easier than using the bottles, cd cases, or whatever. Plus your left with an all concrete structure. Not sure how you would incorporate that into your background build, but it is an idea.

Example of one this guy made

I believe the background thelub is talking about was made by colts1982. I found the thread but there was no pics left. Here is an example though of a pvc 3d background made with pvc, spray foam, and drylok.

Well thank you. I had a similar set up a long time ago. Well it was sorta like this but not really engineered like I wanna do this time. I had it for my eel. But since the cave was actually carefully stacked rocks and not a perfectly sealed environment it could have worked way better. Thats my goal with this.

Originally Posted by vanish

Interesting.

When I say this, I'm not being condescending, I just don't know. What's the desire to have air in the cave?

I didnt take it as condescending. I figured there would be "Why the hell would you go and do all that? kind of questions...

Originally Posted by jungleboy

To keep detritus from building up in the Cave and to force the critters to leave the cave so you can enjoy them

Yep.

Originally Posted by Meep

He pretty much explains it in his post, it's two fold, one it can be drained and flushed to remove build up of debris easily and second for those pesky fish that refuse to leave it would provide an easy means to evict them...

Yep again...

Originally Posted by thelub

I'll have to dig up the background a member here did with 3" pipe. It was pretty cool and I think you could do what you want to do with the air in the system as well.

Ive seen that one I think...

Originally Posted by vanish

Oh Ok, I just wasn't sure if there was something more specific about having air in there. Definitely interesting. I'll be starting on a background next week, so maybe I'll try adding one

please do so i can learn from your efforts... Im for sure not about to start on this tomorrow. Im just to busy and have other projects still to finish. Stand/sump/3478347327 other things...

Originally Posted by CichlidPadawan

I have seen people use balloons to make caves and rocks. Air the balloon up and form concrete around it. Then deflate the balloon and pull it out. Might be easier than using the bottles, cd cases, or whatever. Plus your left with an all concrete structure. Not sure how you would incorporate that into your background build, but it is an idea.

Ive seen those before. In fact, its likely Ive seen like everyone who ever documented their fish tank on the internets tank by now. I have clicked an clicked and clicked for hours. Especially while I was fresh out of surgery.

My plan is to take a little of this and a little of that from lotsa different builds and incorporate them all into my own.

I travel a lot and i need as much of my tank to be as low maintenance and automated as possible. I figure little touches like this in the design will help it be more enjoyable long term and easier to maintain.

My reason for not doing the balloon method is because i want more control over the shape of the interior of the caves.

I plan on having recessed areas that would be more of a cavern than a cave so a large fish can call that area home. in this case the entrance would be the same size as the cave chamber. Basically its just a recessed area in the BG.

Then I want the cave I describe in my OP obviously

And then I want to do something like the link you guys put up where fish can enter the front of a cave and exit the top so its more of a vertical tunnel than a cave.

ANd then thers the internally lit (by fiber optics) feature i didnt mention in my OP.

Oh, and i might have a sandfall. or maybe a couple of them...

I want a lot of stuff LOL

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

Kinda made a lil progress on this. Well, not so much progress but i found my long lost hobby hot knife for cutting styrofoam. I had basically given up on ever locating it and was gonna make one and then there it was in the bottom of my junk drawer. I think its lost some of its strength because I remember it cutting better than it does now but whatever. it still works.

So i was messing around with some scrap Styrofoam and came up with a plan to make my first cave by creating a form for the cave out of styrofoam and then layering it with fiber glass. After the fiberglass hardens ill scoop out the foam and clean it up with acetone. and now im sorta stuck. The design i wanna make is like the one in my original post so ive got the shape figured out BUT i dunno how big to make the inside. id like it house an eel and make it big enough to let the guy feel safe in there and since its likely ill be buying a small eel and watch it grow, im just not sure how big to make the interior.

do eels chill in their caves coiled up? or lay straight out? anyone know. Google has been no help.

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

The styrene solvent in polyester fiberglass resin will dissolve many/most foams, test first... If it melts you will need to paint or seal the foam prior to fiberglassing...

Thanks .

Yea, ive done this before but not for a fish tank. I just coated the foam in painters tape and it worked. iused car wax as a release agent. The fiberglass stuff I have in my garage right now is a different brand than when I did that but im betting it will still work. Ive got time to play with it.

ANy wisdom on the chillin habbits of eels?

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

They had this to say
Attention must also be given to the aquascaping of the aquarium. Most Moray Eels are cave and crevice dwellers, and will thus not appreciate a tank without adequate hiding places. A reef tank with live rock stacked to create caves is sufficient for many species of eel, particularly the smaller varieties. For larger Eels, some engineering of specific caves may be necessary. PVC pipe makes an excellent eel cave. Select pipe that is no more than 50% larger in diameter than your Eel. To allow an Eel more freedom of choice and to accommodate its growth, pipe of several different diameters can be used throughout the tank. The pipe can be set pointing upwards at roughly a 45° angle and the rockwork of the reef built around it. For added aesthetic appeal, small rocks and rubble can be glued to the outside of the pipe using silicone sealant or aquarium-safe glue. PVC can also be used to create a cave in the substrate of a tank. A length of pipe can be laid horizontally under the sand or crushed coral with a 45° elbow and a short length of pipe emerging from the substrate. Rubble can be piled around the pipe where it juts out, creating a very natural look which is made all the more striking by the presence of the front end of an eel waving in the current! A display done by my good friend Anthony Calfo utilized clear PVC for this underground cave. The pipe was situated against the edge of the aquarium so the eel – a beautiful Honeycomb Moray (Gymnothorax favagineus) in this case – could be seen relaxing in his cave.

Some other place said this....
It is better to provide it with several caves and decorate in such a way that it is possible for it to move from on side of your aquarium to the other without being exposed.

Basically everyone and their Mom who has made an eel cave used pvc and that doing anything beyond that is kinda new territory, it looks like i might be kinda pioneering this area. I wish I had more info but oh well LOL.

Since I need a pitched roof on mine (so I can release all the air from inside it) ill have to mod the pipe if use PVC. Ill either split it lengthwise and craft something with fiberglass to give it a single high point in it, mitre cut it so there's a slight peak or just heat up the pvc and bend it. Ive got some scrap stuff around the house im gonna mess with and see what happens. The gears in my head are turning again...

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

I ran zipties through the holes and attached an couple of air lines in there that have little holes in them. these go into a T barbed fitting and exit out the slot i cut out. the airlines that run in there will serve as the air inlet. the hose ends are melted closed.

I used some painters tape to bend the top piece of PVC and got out my hot glue gun and glued the tow pieces together. Ideally I shoulda used aquarium safe sealant but the hot glue dries quickly and this is just a mock up to see if this idea of mine is gonna work so I figured what the hell...

I also drilled a hole in the top and ran an airline through it so it is just barely inside and then glued that inplace. This is how the air will escape when I decide to drain it out. (it will have a valve i can open and close)

Here is what it looks like as it is now...

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

The final portion of this project, at least for the bench test portion of my little build here, is to figure out how to run the hose from the power head into it. I ordered the pump but its not here yet and I dont know the size the hose will be. I also dont want anything to be able to swim into the hose so im gonna make a hole in the bottom center of the bottom piece and cover it with some of that plastic mesh screen stuff they use for needle point. (i forget what its called but i think you guys know what im talking about) then ill attach the inlet hose to the face of that and glue it in place. and seal it up good around the edges. My theory is that the water will flow in and sorta spiral around in there like a tornado and launch out the poop and what not that builds up in there.

I am thinking the hot glue is the weak point here but after this is all wrapped in fiberglass im sure that wont be an issue and the fiberglass will make the structure solid as hell

I also still need to ad some 45 degree angled pieces on each end so the sides are just lower than the floor of the cave. This way it should be able to full fill with air when I fill it. As it sits now, it would let he top portion fill but not the whole thing.

Anyway. thoughts anyone?

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

So I found an old paint brush and laid a little bit of glass. All I did was one side and I wrapped around the top a lil bit where the exit hose is. The main open area is just one layer of glass. Then there's some lil scraps at each end .

Earlier I mentioned that I was gonna add some 45 degree tips to the ends. Well I think doing the mitre cuts might mean I've gotta go right thru the hose on the air diffuser lines right at the ends. And now the zip ties that hold the ends down are coated in resin so there's a lil work there to go still.

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

I wanted to wake up to fully cured piece (and a thicker/stronger one) so after the two hour hardening time I had another session with my lil cave project. Its much thicker now. Should be plenty sturdy for sure.

DISCLAIMER- I was 5 beers deep when I did my last lap with my fiber glass so it is a lil sloppy. Also, I was supposed to lightly sand the first layer before I did it (but I didnt.) Im pretty sure ill be fine though since there was plenty of rough edges and surfaces in the original coat ALso at this point, I had run out of rubber gloves too (so as I type this my fingers are sticky with random tiny strings of fiberglass dangling from them).There's no new pics of my ugly cave tonight because I dont wanna scrape resin off my screen tomorrow. If ya cant already tell by the horrible quality of my cell phone pics, my phone is hammered enough already.

Good news is, while I was tinkering with it, I worked out a solution (in my head) to my air hose diffuser lines being in the way of where I am gonna need to do some modifications. I also started playing with tiny little miter cut sections of PVC. I need to wait till tomorrow (when the fiberglass I lad tonight is hardened) but Im pretty sure I'll gonna have something pretty cool to post for the two entrances (if it works).

Getting my hands dirty on this finally, has put some wind in my sails. And of course along the way I have already run into some things I woulda done differently. Hind sight is 20-20, right? Soon, I should be able to fully bench test this and once I am confident my design works, I will get started on version. 2.0.

Im gonna have one more beer and hit the sack. Should have updates tomorrow.

Note to self- find dremmel tool and buy some new fiberglass brushes and some more glass.

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

I'm very interested to see where you take this. Thank you for exploring new territory.

Thanks. Im curious where this will go also. I wish going to the hardware store wasnt such an ordeal for me right now. Im nursing a broken foot so my ability to get around (and my cash) is pretty limited currently. But im kinda a pack rat, so my garage is filled with stuff i hope to repurpose for this project. I do gotta spend some dough though because I will soon run out of egg crate, fiberglass, and brushes.

BTW, I really like the background you made.

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

Tonight I connected a bunch of tiny miter cut sections of pipe onto the entrances of the cave structure. None of the sections were really measured or anything. I just chopped a buncha lil sections out. I rounded the sharp edges and then joined them with a bead of hot glue.

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

Let's talk about FUNCTIONAL CAVES.

I added some more miter cut pieces of pipe and started fiberglassing it all up.

Next one of these I make I'm probably add the airline stuff LAST.

EDIT- I am also planning to try and craft my next ones so that i do all the fiber glass at the end. (If the structure needs me to glass part of it first i guess i will have to though). My logic here is that i will waste less brushes this way because the brush is a one time use deal and while they arent that expensive, id still like to do a better job of maximizing their usefulness per brush. I might see about getting some of those plumbers brushes they use for copper plumbing. I think they may be cheaper than the disposable brushes im using now.

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

Let's talk about FUNCTIONAL CAVES.

I'm pretty stoked about all the variety I can have by using my mitre saw and some PVC pipe. The joints go together easily with my hot glue gun. All I do is lay a fat bead around one piece and hold it to the other and it secures almost immediately. I use a thick bead because when I put them together it oozes into the inside of the joint on the inside of the pipe and sorta softens the joint and gets rid of any rough edges.

I have my reservations about how well the glue will hold up over time (and submerged) but I'm confident that going over the whole thing with fiberglass will make it sealed and structurally sound.

I need more pipe now and will pick up a variety of sizes hopefully today.

I wanna have this going on all over the place in my BG and now that I'm not limited to just straight pipes and 90 and 45 degree fittings to make bends the possibilities are really pretty infinite.

My tank is 6 feet across and I'd like to have it so my eel can make it from one side of the tank to the other mostly using these tunnels. I'd also like some bigger chambers in there so the eel has the ability to turn around inside of some of them.

Im gonna build a wooden replica of the back, floor and sides of my tank so I can do my whole BG on a table top and know it will fit into the tank (will be made into 3 sections). I expect some challenges with making the tunnels go the full length of the tank since it will be at least three sections but I've got a plan in my head to pull it off.

But my garage/workshop has an engine, transmission and a bunch of other crap in the way right now. (Were swapping a v8 into my roommates truck and pulling out his v6.). Anyway, my workspace is limited right now because it looks like a pickup truck threw up in there. Hopefully I'll have enough space before too long.

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby

You can use traditional PVC cement to but joint your pipe as well, or even go to the vinyl fencing area and get a tube of the white fencing PVC cement that is a little more like caulk... Both are nearly instant bonds as well...

You can also do soft bends in PVC quite easily but just heating it over your stove top or with a heat gun, the pipe will literally turn to spaghetti like if you get enough heat into it...

You can use traditional PVC cement to but joint your pipe as well, or even go to the vinyl fencing area and get a tube of the white fencing PVC cement that is a little more like caulk... Both are nearly instant bonds as well...

I was gonna try the PVC cement method last night actually but unfortunately the stuff I had on hand was all dried up. I do like the way that stuff works though because it really welds the plastic together. I havent heard of the pvc fencing caulk before but Ill look into that. But for now my trusty hot glue gun has been doing the trick pretty well. The draw back to using the hot glue though is two fold. 1. im not sure how long it will last 2. im sure its not structurally sound enough so it needs the fiberglass to reinforce it. I do like the padding it adds to the joints on the interior of the cave when it oozes out though. And, while its messy, im enjoying working with the fiber glass. Its fun and i have another project for my truck i wanna do but i seriously need to polish my fiberglass skills before i try that. This will serve as "practice" since these pieces will all be hidden in my BG and it doesn't matter how ugly they are. (thankfully because this thing is really really ugly)

Originally Posted by Meep

You can also do soft bends in PVC quite easily but just heating it over your stove top or with a heat gun, the pipe will literally turn to spaghetti like if you get enough heat into it...

Im betting i do this at some point too. Ive got torches and an industrial heat gun so i wont need to gather up any new tools to try it.

BUT, the benefit of doing this in sections is it can go together sorta like legos. I can piece it together an inch or so at a time and this gives me a lot of flexibility in my design. If I had a real blueprint of what my collection of caves and tunnels was gonna end up like in the end then i would probably just melt and bend all the pipes but since Im kinda making this a functional art project ill probably just continue with the miter cut method. It gives me more flex to make tiny changes as I go. In the end, this is a journey and I'm not really sure where I will end up.

Out of curiosity, does anyone have any experience with hot glue in fish tanks? Am I headed for failure with this as a material?

If laughter is the best medicine, I am part of its corrupt pharmaceutical lobby